Schistosomiasis is a major health hazard in many regions of the world. Techniques for the diagnosis and treatment of this disease are not yet satisfactory. The aims of this proposal are to isolate and purify specific enzymes of the adult worm of Schistosoma mansoni, to study their biochemical and immunological properties and to determine their utility in the diagnosis of schistosomiasis. These enzymes are acidic thiol-dependent proteinases, which may function in the nutrition of the worm, by digestion of host hemoglobin. These enzymes are regurgitated into the host's circulation, and we isolated two species of proteinases which lead to the production of antibodies in mice, baboons, and humans. The first objective of this proposal is to purify these proteinases to homogeneity and to determine their physical-chemical properties and structures by biochemical and immunological techniques. The second objective is to study the role of these proteinases in schistosome physiology and metabolism by determining the appearance of these enzymes during development, and to study their action on specific host blood proteins including hemoglobin and immunoglobins. The third objective is to obtain information about the structures of these enzymes using genetic and molecular cloning techniques.